Breast pumps are used by mothers to express breast milk at a convenient time, to be stored for later consumption by their child. The breast pump operates by generating a vacuum to mimic the feeding action of the child. Conventional breast pumps can be categorised as mechanical, in which a user manually operates a vacuum pump in order to generate the required vacuum, or electrical, in which a vacuum pump is driven by an electric motor. In electrical breast pumps, it is generally desirable to reduce a power consumption of the system, improve reliability of the system to avoid potential injury to a user, and reduce noise levels associated with the operation of the breast pump. High noise levels can prevent a mother from being able to relax and so the let-down reflex needed to ensure milk expression may be affected.
The invention is made in this context.
US 2008/009815 A1 discloses a closed-loop vacuum control system for a powered breast pump. The vacuum control system includes a source of vacuum for applying a vacuum to a milk collection kit. It also includes a device for setting the vacuum level to be produced by the source of vacuum to a preselected vacuum level. The vacuum control system further includes a sensor for sensing the actual vacuum level being produced by the source of vacuum during operation. A controller continuously compares the preselected vacuum level with the actual vacuum level. A proportional valve is also provided for adjusting the actual vacuum level to correspond to the preselected vacuum level. In this manner, the proportional valve can adjust the actual vacuum level in response to a signal from the controller.